In the art of surgery, stapling has become popular in ligation and division, anastemoses, resection, and skin and facia closing.
Positive aspects of employing staples include decreasing tissue manipulation and handling, speed of applying the staples, and secure fastening. Accompanying the positive features of surgical stapling, however, are problems that have been recognized.
First, the staple should be easily removed once the stapled tissue heals. In this regard, it is desired that the staple remains secured in position and not reorient itself in the tissue after it is applied. Such reorientation may require the staple to be repositioned before removal can be effectuated, which may result in inconvenience for the surgeon and discomfort for the patient.
In addition, I have found that it is desirable to have the two tips of a staple touching after it is applied for best results. The difficulty in this object is that surgical staples may experience spring back following deformation, resulting in a space between the tips.
To achieve the above objects, I provide a surgical staple formed of a material which is preferably heat recoverable and has a memory shape corresponding to the open position of the staple, the material undergoing some spring back after deformation. When the applied staple is to be removed, heat is transferred thereto and the staple returns from a closed deformed shape to the (open) memory shape.
To insure that the applied staple remains properly positioned for removal, the staple in its closed shape forms a square-cornered rectangular. The square corners prevent reorientation of an applied staple in the tissue.
To achieve the object of tip-to-tip contact, the staple is initially closed to provide tip overlap so that, upon spring back, tip-to-tip contact results.
Hence, according to my invention, a surgical staple is applied in such a way that it maintains its position in tissue, provides tip-to-tip contact without large portions of tissue interposed or pinched between the tips, and in general permits facilitated removal at the proper time.
A conventional stapling device is shown in U.S. Pat. No. 4,179,057. In that patent, one staple after another is advanced to a drive position from which the staples can be ejected in succession by the stapling device into the skin. A review of U.S. Pat. No. 4,179,057 indicates, however, that spring back occurring in the staple shown therein would result in further spreading of the tips and a loss of square corners in the closed staple.
The conventional device discussed above and other devices in the art may be modified by my improvement to enable such devices to effectively apply a staple--preferably a heat recoverable staple--that undergoes spring back after deformation while achieving the aforementioned objects.